Mechanisms of Gene Regulation
Vasudevan Simon, Bindu , Ortega, Jose Luis , Bagga, Suman , Sengupta-Gopalan, Champa .
3’UTR mediated transcript turnover may be a general regulatory step in the expression of some isoforms of cytoplasmic glutamine synthetase in legumes.
Glutamine synthetase (GS) is an enzyme that plays a key role in N assimilation by catalyzing the condensation of glutamate and ammonia to form glutamine. There are two major isoforms of GS in plants, the chloroplastic isoform (GS2), and the cytosolic isoform (GS1). While GS2 functions in the assimilation of ammonia produced by photorespiration or nitrate reduction, GS1 assimilates ammonia produced by all other physiological processes. Both GS1 and GS2 are known to be transcriptionally regulated, however, some recent work from our laboratory has shown that a soybean GS1 (GmglnÎ²1) gene is posttranscriptionally regulated by the N status at the level of transcript turnover, the process being mediated by its 3’UTR. The main objective of this paper is to determine if the 3’UTR mediated transcript turnover exhibited by GmglnÎ²1 applies to other GS1 genes. To accomplish this objective, we have made gene constructs consisting of the GmglnÎ²1 coding region engineered individually with the 3’UTR of the two alfalfa GS1 genes (MsGS100 and MsGS13), the GmglnÎ²1, or the nopaline synthetase gene (NOS), all driven by the constitutive CaMV 35S promoter. The constructs have been introduced into alfalfa by Agrobacterium tumefaciens mediated transformation and the putative transformants have been confirmed for the integration of the transgene. The putative transformants will be tested for the expression level of the transgene in the different organs and under different N and C regimens. Preliminary analysis based on agroinfiltration of tobacco leaves of gene constructs with the different 3’UTRs behind the GUS coding regions indicates that the 3’UTR of the MsGS100 but not MsGS13, like the 3’UTR of the GmglnÎ²1 gene plays a role in transcript turnover.
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1 - New Mexico State University, Molecular biology program, Department of plant and environmental sciences, Skeen hall room W329, Las cruces, NM, 88003, U.S.A
2 - NMSU, Plant and Environmental Sciences
3 - NMSU, Plant and Environmental Sciences, Molecular Biology Program
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM